Histopathological and clinical characteristics of duodenal gastrointestinal stromal tumors as predictors of malignancy.

Saito et al. World Journal of Surgical Oncology 201 3, 1 1 :202
http://www.wjso.eom/content/1 1 /I /202

WORLD JOURNAL OF
SURGICAL ONCOLOGY

RESEARCH Open Access

Histopathological and clinical characteristics of
duodenal gastrointestinal stromal tumors as
predictors of malignancy

Tsunenori Saito 1 ' 2 * Masaki Ueno 2 , Yasunori Ota 3 , Yoshiharu Nakamura 4 , Masaji Hashimoto 2 , Harushi Udagawa 2 ,
Kyoichi Mizuno 1 , Kenichi Ohashi 5 and Goro Watanabe 2

Abstract

Background: Although gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the
gastrointestinal tract, they are very rare. This study evaluated clinical and histopathological characteristics of
duodenal GISTs to identify factors useful in predicting prognosis for patients with these tumors.

Methods: A retrospective study was performed on 20 patients who had undergone surgery between 1987 and
2009 for duodenal GISTs. Clinical, histopathological, and immunohistochemical data were evaluated. Survival
analyses were conducted using Kaplan-Meier estimates.

Results: In 12 patients (60%), duodenal GISTs were diagnosed incidentally. Eight cases (40%) were classified as high
risk grade GISTs. Skeinoid fibers (SkF), which are eosinophilic globular hyaline deposits in the extracellular
interstitium of the tumor, were found in 12 patients. Skeinoid fibers were not recognized in 8 cases, and these
included 3 cases (37.5%) where tumors recurred after surgery and the patient died. Tumors without SkF were larger
(81 ±92 vs. 23 ±8 mm, P < 0.001) and had a higher mitotic count (224.0 ±336.6 vs. 0.0 ±0.0 /50 high-power
field, P < 0.001) than those with SkF. Survival time was shorter in patients with tumors lacking SkF (52.9 ± 50.7 vs.
1 08.9 ± 86.5 months, P = 0.01 9).

Conclusions: We have identified clinical and histopathological characteristics that were useful in predicting the
prognosis of patients with duodenal GISTs. In this study, 60% of the tumors were found incidentally, SkF were not
recognized in tumors from 40% of patients, and all cases of post-operative tumor recurrence and death occurred in
this subgroup of patients.

Keywords: Duodenal GIST, Skeinoid fiber, Histopathology, Prognosis, Medical examination

Background

Gastrointestinal stromal tumors (GISTs) are the most
common mesenchymal tumors affecting the gastrointes-
tinal tract [1]. The cells in these tumors show differenti-
ation toward the interstitial cells of Cajal [2]. The majority
of GISTs express a growth factor receptor with tyrosine
kinase activity termed KIT which is constitutively activated.
KIT is the product of the proto-oncogene CD 117 (c-kit)
[3]. In GISTs, morphologic features including mitotic

* Correspondence: tnsaitonms@gmail.com

department of Internal Medicine, Nippon Medical School, 1-1-5 Sendagi,
Bunkyo-ku, Tokyo 1 13-8603, Japan

department of Digestive Surgery, Toranomon Hospital, 2-2-2 Toranomon,
Minato-ku, Tokyo 105-0001, Japan

Full list of author information is available at the end of the article

count and tumor size have been most acknowledged to
be important in predicting malignant tumor behavior
[4]. These tumors are common in the stomach (60-70%
of cases) and small intestine (30%). However, duodenal
GISTs are very rare and constitute less than 5% of all
GISTs [5] . There are very few reports describing duodenal
GISTs [6-9].

Duodenal and intestinal GISTs contain skeinoid fibers
(SkF); eosinophilic globular hyaline deposits found in the
extracellular interstitium of the tumor. The ultrastruc-
tural appearance of SkF is similar to that of the skein of
yarn [10]; however the composition and origin of SkF re-
mains unknown. Several studies [4-7,10,11] suggest that
SkF in GISTs are associated with low tumor proliferative

© 2013 Saito et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
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reproduction in any medium, provided the original work is properly cited.

Saito et al. World Journal of Surgical Oncology 201 3, 1 1 :202
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activity, but the association between SkF in duodenal
GISTs, tumor malignancy and patient prognosis has not
been investigated thoroughly.

The aim of this study was to evaluate the clinical and
histopathological characteristics of duodenal GISTs, to
determine factors useful in predicting patient prognosis.

Methods

Clinical background

A retrospective study was performed using clinical and
pathological data from 20 patients with duodenal GISTs.
Patients who underwent surgery for duodenal GISTs
between November 1987 and May 2009 were enrolled
in the study; 12 had undergone surgery in Toranomon
Hospital and 8 in Nippon Medical School Hospital.
The diagnosis of GIST was confirmed after pathological
review and positive immunoreactivity for KIT. The

Table 1 Characteristics of patients with duodenal GISTs

diagnosis of GIST was also confirmed in KIT negative tu-
mors based on morphology and positive CD34 immuno-
histochemical results. Confirmatory mutation studies were
not performed. The study population comprised 9 men
and 11 women; aged 42 to 79 years (mean 60 ± 12 years).
All patients gave written informed consent within an ap-
proved ethics process. The study was conducted in accord-
ance with the Declaration of Helsinki.Clinical background,
including age, sex, chief complaint, method of GIST detec-
tion, location of GIST in the duodenum, and surgical pro-
cedures used are detailed in Table 1.

Histopathological assessment

The gross features of the duodenal GISTs, including
growth pattern and tumor size, were verified from surgical
and pathological records. Tumor tissue samples were fixed
in 20% neutral buffered formalin, embedded in paraffin,

Variable

Total

SkF group

non-SkF group

P value

Number 20 12

Age - yr (mean ± SD) 59.9 ±11.6 63.6 ±9.8

Male/Female sex - no. (% male) 9/1 1 (45) 2/1 0 (1 6.7)

Presentation reason - no. (%)

Medical check-up 1 0 (50%) 6 (50%)

Bleeding 3(15%) 2(17%)

Anemia 5(25%) 2(17%)

Others* 2(10%) 2(17%)

Diagnostic method - no. (%)

Fiber-optic gastroscopy 14 (70%) 7 (58%)

Abdominal ultrasonography 2(10%) 1(8%)

Upper gastrography 2 (1 0%) 2 (1 7%)

Abdominal computed tomography 1 (5%) 1 (8%)

Operation for another gastrointestinal disease 1 (5%) 1 (8%)

Therapeutic surgical procedure - no. (%)

Partial resection 1 7 (85%) 12(1 00%)

Distal gastrectomy 2(10%) 0(0%)

Pancreaticoduodenectomy 1 (5%) 0 (0%)

Site of tumor in duodenum - no. (%)

1 st portion of the duodenum 5 (25%) 4 (33%)

2nd portion of the duodenum 9 (45%) 5 (42%)

3rd portion of the duodenum 4 (20%) 2 (1 7%)

4th portion of the duodenum 2 (10%) 1 (8%)

Risk of aggressive tumor behavior (modified AFIP consensus criteria) 12 - no. (%)

Very low risk 3 3

Low risk 9 9

High risk 8 0

54.3 ±12.3
7/1 (87.5)

4 (50%)
1 (13%)
3 (38%)
0 (0%)

7 (

1 (13%)
0 (0%)
0 (0%)

0 (0%)

5 (63%)

2 (25%)

1 (13%)

1 (13%)
4 (50%)

2 (25%)
1 (13%)

0
0

0.048
0.003

0.675
0.656
0.296
0.347

0.187
0.653
0.347
0.600
0.600

0.049
0.147
0.400

0.307
0.535
0.535
0.653

0.193
0.001
<0.001

Data expressed as mean ± SD, where appropriate. AFIP = Armed Forces Institute of Pathology.

* One patient's duodenal GIST was detected when she had a gastric smooth muscle tumor resected, and another patient's duodenal GIST was detected i
incidental finding on a computed tomographic scan of the abdomen performed to screen for metastasis of malignant melanoma.

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and sectioned at a thickness of 3 (im. Serial sections were
stained with hematoxylin and eosin, Elastica van Gieson
(EVG) or Elastica-Masson Goldner (EMG), periodic acid
and Schiff (PAS) stain, and diastase treated PAS stain.
Three authors (T.S., Y.O., and ICO.) assessed each sample
for histologic and immunohistochemical evidence of GIST.
We examined the specimens 3 times in random order, with
the pathologist blinded to the clinical background of the
individuals from whom the tumors were removed. Histo-
pathologic evaluations were determined by consensus in
the case of inter-pathologist differences. The following
histological findings were recorded for each tumor: ulcer-
ation of the tumor surface; tumor necrosis; shape of tumor
cell (spindled cell pattern, epithelioid cell pattern, and
mixed spindle and epithelioid cell pattern); nuclear shape
and enlargement; total number of mitoses in 50 high-
power fields (HPF; x40 objective and x 10 ocular lenses),
and presence of SkF, on an Olympus BX-50 microscope
(Olympus Optical Co., Tokyo, Japan).

Immunohistochemistry

Indirect immunoperoxidase staining, with or without
heat-induced epitope retrieval (autoclaving for 5 min in
10 mmol/L citrate buffer, pH 6.0), was performed using
consecutive silane-coated paraffin sections sampled from
the tumor-nontumor junction. The target differentiation
antigens, visualized using monoclonal and polyclonal
antibodies, included smooth muscle markers such as
a-smooth muscle actin (SMA) and desmin, and Schwann
cell-related markers such as S-100 protein. Immuno-
staining was used to detect KIT and CD34. To demon-
strate proliferative activity, paraffin-resistant Ki-67 antigen
was detected immunohostochemically by heating paraffin-
embedded tumor tissue and then staining with MIB-1 anti-
body. The results were evaluated using the following
criteria: negative, focally positive (less than 50% of tumor
cells showing a positive reaction); diffusely positive (more
than 50% of tumor cells stained). The labeling indices of
MIB-1 antibody were evaluated by counting positive nuclei
in 1000 tumor cells.

Classification of aggressive behavior in duodenal GISTs

The malignant potential of the tumors was estimated based
on tumor size and mitotic count, according to the modified
Armed Forces Institute of Pathology (AFIP) consensus cri-
teria for risk stratification of duodenal GISTs [12].

Statistical analysis

The discontinuous variables, such as observational histo-
pathological results and patient numbers for some clinical
parameters, were compared by Fisher s exact method. The
continuous variables, such as clinical data, were eval-
uated by Wilcoxon rank-sum test. Disease free survival
and overall survival were calculated using the Kaplan-

Meier method. Univariate analysis was performed using
the Log-rank test. Statistical analyses were performed
using the SPSS software package (SPSS Inc., Chicago,
IL, USA). All data were expressed as the mean ± SD.
P values < 0.05 were considered significant.

Results

Clinical findings, tumor location, and surgery

The baseline clinical characteristics of patients with duo-
denal GISTs are summarized in Table 1. Gastrointestinal
hemorrhage, manifested by hematemesis or melena, was
the most frequent symptom. Ten (50%) of patients were
asymptomatic and incidentally detected during physical
examination for investigation of another disease. In 2
patients, the tumor was incidentally detected during a
medical procedure or abdominal surgery performed for
another reason. In the first patient the duodenal GIST
was detected during resection of a gastric smooth muscle
tumor, and in the second patient the duodenal tumor was
identified in a computed tomographic scan of the abdomen
performed to screen for metastatic malignant melanoma.

Of the 20 duodenal GISTs, 5 were in the 1st portion
of the duodenum, 9 in 2nd portion, 4 in 3rd portion,
and 2 in 4th portion. Fourteen patients were treated with
segmental duodenal resection, 3 cases had tumor resec-
tion, 2 cases had distal gastrectomy, and 1 patient had
pancreatoduodenectomy. Two patients who had distal
gastrectomy performed, had GISTs located in the 1st
portion of the duodenum. One of these two cases had a
complicated smooth muscle tumor in the pyloric part
of stomach. There were no cases of acute abdomen
prompting emergency surgery. There were also no neuro-
fibromatosis type 1 patients with small intestinal GISTs.
A patient, with a 32 mm diameter duodenal GIST, received
400 mg per day of Imatinib (STI571, Gleevec®) preopera-
tively for 2 months, but as there was no apparent effect on
the tumor, tumor resection was performed.

Histopathological and immunohistochemical findings

Mean tumor size was 32 ± 27 mm. Ulceration was recog-
nized in 15 cases, and coagulation necrosis of the tumor
was seen in 6 cases. Twelve cases were classified as hav-
ing a spindle cell pattern, 7 cases had an epithelioid cell
pattern, and one case had a mixed spindle and epithelioid
cell pattern. Nuclear pleomorphism was usually moderate.
The mitotic count in the 20 duodenal GISTs ranged from
less than 1 to 934 mitotic figures 150 HPFs (mean: 89.6 ±
233 /50 HPFs). The mitotic count was <5 /50 HPFs in
14 cases (70%), and 4 tumors (20%) had more than 50
mitosis /50 HPFs. All 20 cases had documented KIT
positivity. Two cases showed KIT positivity in less than
30% of the tumor cells. CD34 reactivity was seen in 14
cases (70%), S-100 was positive in 14 cases (70%), a-SMA
was reactive in 14 cases (70%), and 11 cases (65%) were

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positive for desmin. These immunohistochemical findings
were not found to be significantly associated with malig-
nant behavior in duodenal GISTs or patient prognosis. All
GISTs had positive reactivity for MIB-1. The MIB-1 index
of duodenal GISTs was 1.8 ± 1.2 (range 0.15-60).

Association of clinical factors and presence
of skeinoid fibers

Skeinoid fibers, which are variably sized eosinophilic
globules, were located between tumor cells and were
surrounded by an artifact-like empty halo (Figure 1).
These fibers stained positively with PAS stain, and nega-
tively with EVG and EMG stains. Their diastase treated
test was also negative. Skeinoid fibers also showed no
immunoreactivity with KIT, CD34, a-SMA, desmin, and
S-100. These fibers were recognized in 12 duodenal
GISTs (SkF group), with the other 8 tumors lacking these
fibers (non-SkF group). Clinical differences between these
2 groups are shown in Table 1 and pathological differ-
ences in Table 2. The GISTs size in the non-SkF group
was significantly larger than in the SkF group (81 ± 92 vs.
23 ± 8 mm, P < 0.001). All tumors in the non-SkF group
were ulcerated. Tumor necrosis was present in 6 tumors:
all in the non-SkF group. Cellular shape (spindle or epi-
thelioid cell pattern) had no correlation with presence of
SkF. The mitotic count and MIB-1 index in the non-SkF
group was also greater than that in SkF group (224.0 ±
336.6 vs. 0.0 ± 0.0 150 HPF, P < 0.001; and 26.3 ± 20.3 vs.
1.8 ± 1.2, P < 0.001, respectively).

Classification of aggressive behavior in duodenal GISTs

According to the modified AFIP consensus criteria for risk
stratification of GISTs [12], in this study there were 3 tu-
mors in the very low risk category, 9 in the low risk, and 8
in the high risk. All patients with tumors in the SkF group
were classified with either a very low or a low risk of ag-
gressive tumor behavior, and those in the non-SkF group
with high risk of aggressive tumor behavior Figure 2.

Survival and tumor recurrence

Seventeen (85%) patients were alive with no evidence of
disease for a median survival time of 6.0 years. Overall
tumor-specific mortality was 15% (3 of 20) in patients
with follow-up. Of these patients, one was a woman and
two were men. Their duodenal GISTs recurred a mean
of 9.6 ± 5.8 months after the initial operation. One pa-
tient had liver metastasis and two patients had abdom-
inal metastasis. They died due to this disease a mean of
49.9 ± 68.3 months following recurrence, all being in the
no SkF group. We performed a combination analysis
using the Kaplan-Meier method (Figure 3) and Log-rank
test, both of which showed that the non-SkF group had
a significantly shorter survival time (52.9 ± 50.7 vs. 108.9 ±
86.5 months, P = 0.019).

*

Figure 1 Histopathological findings in duodenal gastrointestinal
stromal tumors, (a) 61 year old woman without recurrence
post-operatively. The tumor, size 33 mm, consists of spindle cells with a
fascicular arrangement. Skeinoid fibers (SkF, *) are seen between the
spindle cells (hematoxylin and eosin stain), (b) and (c) 61 year old
woman without tumor recurrence post-operatively. The tumor size was
25 mm. Periodic Acid-Schiff reactivity is positive in SkF (b) and negative
in the diastase digestion test (c). Scale bar = 100 urn in a, b, and c.

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Table 2 Pathological and immunohistochemical findings in duodenal GISTs, and a list of primary antibodies
used in diagnosis

Variable

Dilution, Source of Antibodies

Total

SkF group

non-SkF group

P value

Number

20

12

8

Tumor size - mm

46.5 ± 63.4

23.3 ± 8.2

81.2 ±92.2

<0.001

Spindle type cell - no. (%)

13 (65%)

8 (67%)

5 (63%)

0.608

Necrosis - no. (%)

6 (30%)

0 (0%)

6 (75%)

<0.001

Ulceration - no. (%)

15 (75%)

7 (58%)

8 (100%)

0.051

Mitosis - no. per 50 HPF

89.6 ±233.3

0.0 ± 0.0

224.0 ± 336.6

<0.001

Mib-1 index -%

1:200, autoclave; MBL

1 1 .6 ± 1 7.4

1 .8 ± 1 .2

26.3 ± 20.3

<0.001

KIT - no. (%)

1:100, autoclave; Dako

20 (100%)

12 (100%)

8 (100%)

0.999

CD34 - no. (%)

1 :1 00, autoclave; Ventana

14 (70%)

9 (75%)

5 (63%)

0.455

S-100- no. (%)

1:1000; Dako

14 (70%)

9 (75%)

5 (63%)

0.455

a-smooth-muscle actin - no. (%)

1:200, autoclave; Dako

14 (70%)

9 (75%)

5 (63%)

0.455

Desmin - no. (%)

1:40, autoclave; Dako

1 1 (55%)

8 (67%)

3 (38%)

0.205

Data expressed as mean ± SD, where appropriate.

Discussion

The present study showed that duodenal GISTs, without
any metastasis or local invasion, may be completely cured
by early resection. In this study, 12 cases had SkF in the
extracellular interstitium between tumor cells. In our ob-
servation, all tumors containing SkF were of low grade ma-
lignancy; the prognosis for patients with duodenal GISTs
with SkF was significantly better than for those with tu-
mors lacking SkF.

Predicting the malignant potential of GISTs may be diffi-
cult, and there is currently no consensus on risk estimates

Figure 2 Histopathological features of a duodenal gastrointestinal
stromal tumor. 44 year old man with tumor recurrence after
resection; recurrence detected as hepatic metastasis and peritoneal
disseminations. Tumor size was 110 mm. Tumor showing proliferation
of spindle cells arranged in interlacing bundles. There were no skeinoid
fibers in this tumor (hematoxylin and eosin stain). Scale bar = 00 urn.

for metastasis to the liver or peritoneum, or for patient
mortality. For example, small tumors with a low mitotic
rate may still metastasize. Further, GISTs in the small
intestine seem to behave more aggressively than gastric
GISTs of similar size and mitotic activity [12,13]. Miettinen
et al. [7] proposed that duodenal GISTs whose mitotic
count exceeded 2 mitoses /50 HPFs be regarded as high
grade malignancies. However, prominent nuclear pleo-
morphism and hyperchromasia are rare in duodenal GISTs.

1.0

0.8

0.6

0.4

0.2

0.0

SkF group

non-SkF group

0 50 100 150 200 250 300

months

Figure 3 Disease-specific survival after resection of duodenal
GIST. Patients without skeinoid fiber (SkF, n = 8) had significantly
worse survival than those with SkF (n = 12, P = 0.019).

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Mortality also occurs in patients whose duodenal GISTs are
large, even if the mitotic count is low, so that tumor size is
the most important factor in grading malignancy of duo-
denal GISTs. Early diagnosis and resection of duodenal
GISTs, improves patient prognosis.

Japanese proactively seek medical examination includ-
ing fiber-optic gastroscopy (FGS) and abdominal ultra-
sonography. This enables early detection of duodenal
GISTs. In our study, 12 of 20 duodenal GISTs (60%)
were found incidentally, and 5 of these 12 cases were
detected endoscopically. In addition, 7 cases (35%) were
recognized by FGS performed to investigate the cause of
gastrointestinal bleeding or the cause of anemia. Therefore,
12 patients (60%) had their duodenal GISTs detected by
endoscopy. In our study, 60% of patients were at very low
or low risk from aggressive tumor behavior according to
modified AFIP consensus criteria for risk stratification of
GISTs, in which the main contributor to risk is tumor size
[12]. Gastrointestinal stromal tumors in Japanese patients
have been reported to contain similar genetic mutations to
GISTs in patients from other countries [14]. The early de-
tection of GISTs allows prevention of metastasis or local
tumor invasion and improved prognosis for patients with
duodenal GISTs.

The composition of SkF is still unknown. These fibers
were present between tumor cells and were surrounded
by an artifact-like empty halo; suggesting SkF were com-
posed of solider elements than tumor cells. Skeinoid fibers
appear as tangles of fibers similar to regular collagen, with
cross-banding of 41-45 nm periodicity, and their length
are shorter than normal collagen fibers [15]. Some studies
reported that SkF contain type VI collagen [10,15,16]. We
regard SkF to consist of a type of polysaccharide because
they stain positively with PAS and negatively with the dia-
stase digestion test (Figure lb and c). They also show
no immunoreactivity with KIT, CD34, a-SMA, desmin,
or S-100 immunostaining.

In this study, all duodenal GISTs with SkF in the
extracellular interstitium were categorized as very low or
low risk according to the modified AFIP criteria for risk
stratification of GISTs, and 8 cases lacking SkF were cat-
egorized as high risk due to their size and number of mi-
toses. These results suggest SkF are associated with less
aggressive behavior in duodenal GISTs. We hypothesize
that the material SkF are composed of has been secreted
from tumor cells and retained in the extracellular space.
Highly malignant GISTs grow rapidly, suggesting that
secretion of the SkF material does not have time to
accumulate in rapidly proliferating highly malignant duo-
denal GISTs.

Genetic research has shown that GISTs with spindle
type cells and those with SkF contained a c-kit mutation,
and GISTs with epithelioid type cells and those without
SkF had an internal tandem duplication in exon 11 of

PDGFRA mutation [17]. This led to the hypothesis that
SkF may be a product of c-kit. However in our study,
there was no relationship between tumor cell type and
presence or absence of SkF, and SkF showed negative
reactivity on KIT immunostaining. PDGFRA encodes a
cell surface tyrosine kinase receptor for members of the
platelet-derived growth factor family. It is located near to,
and is structurally similar to, c-kit, leading to speculation
of a similar origin for both genes. Therefore, this study
suggests there may be no association between either gene
and SkF.

In this study, patients with duodenal GISTs containing
SkF experienced better overall survival than patients
with duodenal GISTs lacking SkF (100% vs. 62.5%). All 3
patients that died in the follow up period in this study
suffered tumor recurrence within half a year, and their
original tumor sizes were over 50 mm. No tumor recur-
rence or metastasis occurred in patients in this study,
when tumors were small and were resected completely.
Although the current classification of GISTs is appropri-
ately based on tumor size and number of cellular divi-
sions counted, adding the speed of tumor growth as an
indicator of tumor malignancy may further improve the
current risk classification system. Miettinen et al. [7]
detected SkF in 78 (53%) of 148 patients with duodenal
GIST, and 70 of these cases were classified as very low or
low malignant potential. This is similar to our results,
however no statistical evaluation of the correlation between
SkF and survival was performed. To our knowledge, the
present study is the first to evaluate the association of SkF
with prognosis in duodenal GISTs.

The major limitation of this present study was the
small number of patients with duodenal GISTs, although
our study does describe 20 cases with adequate follow
up seen in 2 institutes. The largest study on 156 cases
with duodenal GISTs was performed at the Armed Forces
Institute of Pathology (and the Haartman Institute of the
University of Helsinki) between 1970 and 1996 [7]. The
second-largest study had 22 patients [6], and the third-
largest one had only 20 patients [8]. Thus, as a general
trend, cases with duodenal GISTs are few in number be-
cause the duodenum is a short organ. Duodenal GISTs in
Japanese are able to be detected early because of the so-
cial background of proactive medical examination, and
this early diagnosis may facilitate research into the early
biological characteristics of this relatively unusual tumor.
A multicenter study on duodenal GISTs must thus shed
further light on the biologic behavior of this tumor.

Conclusions

We have identified clinical and histopathological factors
that are useful in predicting prognosis in patients with
duodenal GISTs. In this study, 60% of the tumors were
found incidentally. Skeinoid fibers were not recognized in

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Page 7 of 7

tumors from 40% of patients; all cases of post-operative
tumor recurrence and patient death occurred in patients
with duodenal GISTs lacking SkR

Consent

Written informed consent was obtained from the pa-
tient for publication of this report and any accom-
panying images.

Abbreviations

EMG: Elastica-Masson Goldner; EVG: Elastica van Gieson; GIST: Gastrointestinal
stromal tumors; HPF: High-power fields; PAS: Periodic acid and Schiff;
SkF: Skeinoid fiber; SMA: Smooth muscle actin.

Competing interests

The authors declare that they have no competing interests.
Authors' contributions

ST, UM, NY, and WG designed and conducted the study. ST, OY, and OK
analyzed the data, especially pathological evaluation. HM, UH, and MK
helped to write the manuscript. WG is the principal investigator, revised and
edited the manuscript. All authors approved the final manuscript.

Author details

department of Internal Medicine, Nippon Medical School, 1-1-5 Sendagi,
Bunkyo-ku, Tokyo 1 13-8603, Japan, department of Digestive Surgery,
Toranomon Hospital, 2-2-2 Toranomon, Minato-ku, Tokyo 105-0001, Japan,
department of Pathology, Toranomon Hospital, 2-2-2 Toranomon,
Minato-kuTokyo 105-0001, Japan, department of Surgery, Nippon Medical
School Hospital, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan,
department of Pathology, Yokohama City University Graduate School of
Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan.

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tumors of the jejunum and ileum: a clinicopathologic,
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with gastrointestinal stromal tumors. Human Pathol 2007, 38:679-687.

13. Emory TS, Sobin LH, Lukes L, Lee DH, O'Leary TJ: Prognosis of
gastrointestinal smooth-muscle (stromal) tumors. Am J Surg Pathol 1999,
23:82-87.

14. Sakurai S, Oguni S, Hironaka M, Fukayama M, Morinaga S, Saito K: Mutations
in c-kit gene exons 9 and 13 in gastrointestinal stromal tumors among
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doi:1 0.1 1 86/1 477-781 9-1 1 -202

Cite this article as: Saito et al:. Histopathological and clinical
characteristics of duodenal gastrointestinal stromal tumors as predictors
of malignancy. World Journal of Surgical Oncology 201 3 11 :202.

Received: 19 February 2013 Accepted: 5 August 2013
Published: 16 August 2013

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